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A question about barrel length
As I look at different models I find that quite often there are guns that come with 3 different barrel lengths, but are otherwise identical internally ( I assume).
I understand the benefits of having a shorter barrel for CQB play, but how much benefit, if any, do the longer barrel sizes give you when it comes to range and accuracy? At what point does increasing length deliver diminishing returns? |
Read the part about barrels
http://www.airsoftcanada.com/showthread.php?t=166583 TLDR; longer barrel makes absolutely ZERO difference what so ever at the muzzle energies we play at, it is purely aesthetic. |
the size of barrel has two things:
1. where the air window should be places inside your gearbox for maximum performance 2. how much stuff you want to attach to it. Aside from these points, there is not difference in terms of performance. When it comes to CQB, I opt for 416 or MP5 as smaller size allow for very good manuver around corner. I have not played outdoor and I am not a sniper. The best idea is to go to store and hold the actual gun. If you go out to play, ask people about the piece and see if they allow you to hold it for testing. |
Here is a definitive answer for you. At least accuracy wise.
You will not see any more accuracy/consistency benefit after 450mm length. This is kind of the sweet spot that allows your spin from your hop up to stabilize but not so much as to start having irregularity down the barrel. That being said if you need a smaller one for cqb you will probably fine. Edit: if you're an aeg player you will need to match your cylinder volume. (I'm not an aeg player so I'm uneducated about the subject.) |
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My mp5k I had, with a pistol length barrel, could shoot as far as my m4 with 510mm inner. Both around 400fps both with promy flat hops. There was maybe a slightly better grouping at max range with the longer barrel. But the stock on the long gun could likely be the difference. |
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If my pistol can get a 4" grouping at 150ft with it's miniscule 3" barrel, then how will adding another 13.5" of barrel will somehow make that any better? Guy spends $3000 on a CQBR ptw, there's a reason he spent it on a CQBR instead of a 16" DMR. And that reason is, they have the exact same range and accuracy. |
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The OP asked what length is best and that's the answer. |
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Sounds like a lot of american bullshit tech blabber to me.
#1 point that gives away the fact he doesnt know what he's talking about is he thinks pistons can cause suck back in high RoF builds. At 300fps it takes a BB less than 65ms to leave the barrel. At 60rps thats a 166ms cycle time And it takes around 30ms for the piston to come all the way forward That leaves 35ms for the BB to leave the barrel while the gear train is taking 166ms to do a full cycle There's no suck back. There's a loss of lressure at best but no way in hell you'll ever be able to create a suction force to stop the BB in the barrel to cause a misfeed. Furthermore, if he thinks that is whats causing misfeeding in high rof builds, then he doesnt understand high rof builds. I have a simpler explanation that makes a hell of a lot more sense; Its easier to aim a longer rifle than a shorter one. Your own personal accuracy is going to be better with a 30" barrel rifle thats hard to swing around versus a 9" barrel rifle thats pointing all over the place. If his theory had any ounce of truth, then a pistol with a 3" barrel would be very easily notably less accurate at 160ft than a 16" rifle. And yet it's not. |
In airsoft, the barrel is only a method to confine air to accelerate the bb. The accuracy and range come entirly from the hop up. The best barrels are the ones that touch the bb the least and if they do, affect it the least.
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lol suckback.
There are so many other places to draw air from, I guarantee you it's not trying to suck it back from the barrel. longer rifle allows for slightly better aim down the sights, sure. Longer guns are far more cumbersome though. Length of the barrel has less effect in airsoft than people are led to believe, I get similar results from my 229mm mp5 vs my 407mm g36. smoothest, most consistent bore of barrel matters, not length. Quality of airseal and hopup are the most important in getting more precision out of the rifle. Higher weight, higher grade BBs also help. |
Anyone that thinks suck back is a thing is an absolute moron. The suck back theory is a poorly thought out idea made by people suffering from tappet plate pre engagement who were too stupid to figure out how to solve the issue at hand. Suck back is not possible because the nozzle breaks the seal with the barrel before the piston even begins to retract. The guy that wrote that has no idea how to build high end AEGs.
As far as barrel length and accuracy goes, most people seem to think 300-450 is the ideal barrel length. I think that that's all blabber. I had a M14 with a 550mm Prometheus barrel. I had setups with 509, 455, 433, 407, 363, 318, 300, 285, 260, and 247mm Prometheus barrels. Accuracy was pretty much the same. The reasoning for the theory that 450mm is the longest effective barrel length for AEG makes sense, in that after a certain point you run out of air volume and pressure to center the BB in the barrel. If you have a flawless air seal and are shooting 400 FPS or higher, than you can exceed 450mm without detrimental effects to accuracy. The easiest way to determine the longest barrel length your setup can support is to gradually try longer barrels until you stop gaining FPS from having a longer barrel. From 509mm to 550mm I went from 445 FPS to 455 FPS. |
I'm not supporting his suck back theory cause I have no knowledge of aeg's but the BB rolling on the top of the barrel theory seems pretty sound to me.
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I don't see how the bernoulli effect is supposed to have any correlation to a BB rolling in a tube. You're comparing wings and balls here. And obviously when a wing touches the ground and changes angles it's going to send whatever it's attached to in a different direction. It's like you're saying if a planes wing fell off or was damaged mid flight that it's some how comparable to a ball spinning. This ball is being held to the top of the barrel via "the magnus effect" and pressurised air or Gas that it is rideing on.
You would be better off comparing it to a wheel. |
Didn't BB Bastard or someone test these theories with lexan barrels and high speed cameras?
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The magnus effect doesnt even work at high speeds, in the way we're using it.
And the high barrel pressure keeps he BB centered, and the magnus effect not working. If the magnus effect was strong enough to lift the BB in the barrel, then it would start acting immediately as it left the barrel, but the magnus effect doesnt come into play until about 50ft out. Then its a very gradual increase in effect as the BB slows down and its able to move more air around to generate an airfoil. But what makes it really impossible in high pressures is the BB is being PUSHED by the air. Air is pushing past the BB and bleeding past faster than he backspin can move air. At 400fps on a short barrel, a BB would have to be spinning fast enough to push air backwards PAST a 90-120psi compression wave in order to start generating lift. The magnus effect only works at certain speeds where the BB can actually grip and move air in the direction it needs to in order to create that effect. If the BB is travelling faster than it can generate an airfoil effect, then it wont generate an airfoil. The slower the BB is going, the more the magnus effect will affect it. If you look at a wing at high speeds, it generates lift up until it goes supersonic. Then the aerodynamics change. If a BB were to go supersonic, it wouldnt matter how fast it was spinning, it would never generate any lift. And if you have a pressure wave flowing back to front over your wing which outpressures anything in front of the wing, its never going to generate any lift. |
The point is
1. If the BB rolled on the top of the barrel, it would cut off the airflow required to push the BB upward. Otherwise you could drive a car on a ceiling if the Magnus effect applied to wheels touching a surface. 2. The Magnus effect applies to objects moving through air, not object being propelled by air. Read less bullshit on tech forums, learn more about physics and use rational thinking. |
At OP, no barrel length isn't a big factor in the accuracy equation of airsoft. The hop-up unit and BB quality have more to do with that.
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...I want supersonic BBs.
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Well then why does every wide bore barrel manufacturer claim that it does what this guy is saying.
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Every wide bore barrel manufacturer claims to give a better air cushion. I don't recall any manufacturer claiming that bbs ride the too of the barrel. If they did, TK twist barrels would have had really fucked up trajectories.
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I'm just going to concede the argument here. I've probably been swindled by some bad information.
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Most of those opinions were cultivated out of subjective information. The wider the bore the stronger the cushion required to stabilize the BB, so wider bore barrels do work, but so do ones that are tighter. Really tight barrels can have varied results on stability though. Barrel length can have an affect on distance/accuracy, but it isn't the go-to dynamic to improve those things, it might make things worse as well.
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The truth of widebores is they just lose accuracy more slowly over many shots due to fouling. But most people dont even clean their barrels more than once a year, so what do they care about lessened fouling? A 6.23 is supposed to be more accurate. But a 6.03 and 6.23 have the same accuracy. People claim a 5.98 or 6.01 is more accurate. Again, no different than the 6.03 or 6.13 or 6.23. The tighter barrels foul faster, thats about it. I got a one shot kill at 300ft a few weeks ago with my M14; its using a 300mm pdi 6.05 with a suppressor. Heres the kicker; theres more empty space in front of the barrel to the end of the suppressor (310mm) than there is actual inner barrel in the gun. I know a guy with a bolt action rifle with a 550mm 6.01 barrel that can make the same shot, but one has to wonder; whats the extra 250mm of barrel really doing? Its just more length for something to go wrong. The barrel industry has many examples of bullshit theory being used to sell barrels; -edgi 5.98 barrels -TK twist barrels -prometheus delta strike -those new one piece inner/outer barrels Fact is, the BB and hop rubber you use is going to have way more effect on accuracy than the barrel. The worst thing a barrel can do to your accuracy is obstructing the BB; if it hits something in the barrel on the way through, it knocks the rotational axis of the backspin off centerline. But beyond that, the barrel makes very little difference in accuracy at 200-300ft All it does is send the BB out in a straight line and hopefully not affect the rotation. The BB ideally never touches the wall, so bore doesnt matter. The BB is stabilized to the center of the barrel in the first inch or so, so length doesnt matter except for ease of acceleration. The only really important qualities are the consistency of the bore and the finish, so as to reduce any turbulent air flow in the barrel. At 200+ft accuracy is almost entirely determined by BB weight, quality, and how consistent and perpendicular to the ground the backspin is. Because using a king arms .30g BB over a madbull .30 is going to have way more effect on accuracy than using a stock marui barrel over a prometheus 6.03 at 250ft |
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